High-speed ground effect vehicles

ABSTRACT

A ground-effect vehicle comprising air cushions normally confined by solid walls, the front and rear walls of the front and rear air cushions, symmetrically with respect to the longitudinal axis of the vehicle, including portions which are orientatable to permit the cushions to be supplied by ram pressure when the vehicle is travelling at high speed.

United States Patent Bertin [4 1 May 16, 1972 [54] HIGH-SPEED GROUNDEFFECT VEHICLES [72] Inventor: Jean Henri Bertin, Neuilly-sur-Seine,

France [73] Assignee: Bertin & Cie, Boite Postale Plaisir, France 22Filed: Nov. 6, 1969 I 21 Appl.No.: 874,149

[30] Foreign Application Priority Data Nov. 8, 1968 France ..173226 [52]U.S.Cl ..l80/l2l, 180/116, 180/117,

180/126 [51] Int. Cl ..B60v U08, B60v 1/04 [58] Field ofSearcIi..180/117,120,126,119,121

[5 6] References Cited I UNITED STATES PATENTS Dornier ..180/l20 X3,191,705 6/1965 Jones et a1. 180/126 3,221,831 12/1965 Weiland....3,220,501 11/1965 Lande ..180/1 19 X FOREIGN PATENTS OR APPLICATIONS955,923 4/ 1964 Great Britain 180/1 17 936,763 9/1963 Great Britain180/1 17 Primary Examiner-A. Harry Levy Attorney-Stevens, Davis, Miller& Mosher [5 7] ABSTRACT A ground-effect vehicle comprising air cushionsnormally confined by solid walls, the front and rear walls of the frontand rear air cushions, symmetrically with respect to the longitudinalaxis of the vehicle, including portions which are orientatable to permitthe cushions to be supplied by ram pressure when the vehicle istravelling at high speed.

13 Claims, 12 Drawing Figures PATENTEDMAY 1s 1.912

SHEET 3 OF 6 FIG. :5

FIG 4 PATENTEDm 16 I972 SHEET 5 BF 6 HIGILSPEED GROUND EFFECT'VEHICLESBACKGROUND OF THE INVENTION This invention relates to ground-efi'ectvehicles, and has for its object to improve the efiiciency of thesevehicles and to increase the speed which they can attain, while at thesame time simplifying the production of the skirting arrangements whichdelimit the cushion and which extend substantially parallel to thenormal direction of displacement of the vehicle, stabilizing the latteraerodynamically.

The invention also introduces a quite different concept into the designof these vehicles compared with the design concept upon which presentoperational A.C.V. are based. 7

The invention relates essentially to a rationalization of thearrangement involving the layout of the air-cushions and the air flowused to supply these cushions. It makes it possible to combine at zerospeed or at moderate speed the advantages of cushions of pressurizedfluid of the plenum chamber" kind, defined by solid walls, and at highspeed the advantages of utilizing to the full the dynamic pressure ofthe air or ambient fluid for lift of the vehicle. It also enablesrecovery of the ram momentum by appropriate layout of the air or fluidsurface, thus enabling the transfer losses to be reduced to a minimumand the residual momentum to be used for propulsion.

As those skilled in the art will appreciate, the displacement of avehicle of the ground-effect kind through the ambient air is resisted byaerodynamic forces the sum of which makes up the overall drag of thevehicle. This drag is obviously a loss which is subtracted from theforce supplied by the propulsion system. This drag includes the pick-upor ram drag of the air, which is the loss fraction from the energyinitially possessed by the intake fluid, which energy loss can be verylarge at high speeds.

This ram drag is due on the one hand, to the pressure losses experiencedby the intake air in the ducting arrangements, and on the other hand tothe fact that the air escapes from the cushion in all directions, themomentum which it has developed thus having a resultant of zero.

OBJECT OF THE INVENTION The invention aims to make it possible to reducethese pressure losses by discarding the cushion supply ducts and/orreducing their lengths as far as possible, these ducts, when retained,furthermore involving only very slight or for that matter no changes indirection, and by directing towards the rear a substantial proportion ofthe leakage airflow so that said flow contributes to the propulsion ofthe vehicle.

BRIEF SUMMARY OF THE INVENTION In accordance with one aspect of theinvention, the upper lift surface of the confining area, or ceiling, ofthe aircushions, extends symmetrically to either side of that part ofthe vehicle designed to carry the payload, and over part of the area ofthe said ceiling of the air-cushions, to either side of said payloadpart, at least one variable direction injector type static pump orventuri device is located, which device serves to supply air underpressure to the aircushion below, while the lateral confining walls orskirts of the cushions comprise, at the front and the rear of themachine, portions which are likewise orientatable, that is to sayvariable in direction.

The facility for varying the direction of said wall portions and of saidventuri devices makes it possible to regulate the airflow supplying theair-cushions in accordance with the speed of the vehicle.

The supplying of each aircushion through at least one venturi opening toeither side of the central payload or passengercarrying part, anddirecting air into the cushion located therebelow, makes it possible toreduce to a minimum the distance travelled by the supplied air, inparticular when stationary and at low speeds, while at high speeds theopening of the front and rear portions of the confining walls or skirtsof the cushion enables direct supply by the ram effect to be achieved atthe same time as the major part of the leakage FURTHER FEATURES OF THEINVENTION In accordance with another aspect of the invention, whicharises out of the fact that it is expedient to provide, for thestability of the vehicle, not only air-cushions located at either sideof the longitudinal vertical plane of symmetry (for roll stability), butalso cushions located one behind the other from the front to the rear ofthe machine (for pitch stability) the confining walls of the cushion atthe front and at the rear respectively comprise a front portion and arear portion which are each orientatable, and, moreover, the wallseparating two successive cushions comprises likewise an orientatableportion in order that, at high speeds, all the successive cushions canbe supplied with air by the ram effect.

v DESIGNATION OF DRAWINGS The ensuing description relating to theaccompanying drawing will indicate by way of a non-limitative examplehow the invention may be carried into practice.

In the drawings:

FIGS. 1 and 2 are schematic views illustrating the features of theinvention;

FIG. 3 illustrates, in perspective, an embodiment of a ground-effectvehiclein accordance with the invention;

FIG. 4 is a plan view of the machine;

FIG. 5 is a front elevation;

FIG. 6 is a side elevation;

FIG. 7 is a longitudinal section on a larger scale, taken on the lineVII-VII of FIG. 4;

FIG. 8 is a transverse detailed section on the line VIII'VIII of FIG. 6,on a likewise enlarged scale;

FIG. 9 again on a larger scale and in section similar to that shown inFIG. 7, illustrates the detail of the fairings carrying the bores whichform the intake jets of the venturis;

FIG. 10 is a section through one of these fairings taken on the lineX--X of FIG. 9;

FIG. 11 shows a partial section of a device for controlling mobileelements or flaps;

FIG. 12 illustrates in section and on a larger scale, a detail of FIG.11.

DESCRIPTION OF EMBODIMENT Considering FIG. 1, there can be seen a wall awhich, located below the platform b of a' ground-effect vehicle,delimits beneath said platform an enclosure of generally cupped orbell-shaped form, for an air-cushion. The pressurized air is supplied tothis enclosure through a duct c connected to the delivery side of apressurized air generator d, for example a compressor or a venturi.

As those skilled in the art will appreciate, this kind of deviceoperates by its development, through the effect of the pressure of thetop wall of the chamber delimiting the cushion, of a vertical force Fwhich lifts the vehicle so that the walla clears the surface g of theground or water to a height at which an equilibrium condition isestablished. This condition is characterized by a certain leakage heightbetween the surface g and the bottom edge of the walla. The air-cushionsof this kind are referred to as plenum chambers or bell cushions". Theyenable the vehicle to lift until contact between the solid parts of thevehicle and the ground or water is broken, and this gives rise to anumber of known advantages.

In order to recover the dynamic pressure (ram pressure) of thesurrounding fluid, it has been proposed that the intake h for this fluidshould be provided facing towards the front of the vehicle, the lattermoving in the direction of the arrow F At high-speed, the pressurizedair generator d can even be switched out and the air-cushion suppliedsolely by ram pressure. However the duct c, with its elbow or elbows, aswell as the generator 0!, introduce pressure losses and thus reduce theefficiency of pick-up by the frontal orifice h.

In accordance with a feature of the invention, an intake orifice for thedirect entry of air is formed in the wall of the cushion. This can beeffected in the manner shown in FIG. 1 by designing that part of thesolid wall a, which faces in the forward direction of the vehicle, inthe form of a flap 1 which is of flexible type or is articulated at 2,so that the opening of this flap, at an adequate ram pressure, enablesthe air-cushion to be supplied directly. The pressurized air generatorcan then be switched out and the duct c can even be closed off ifdesired.

n the other hand, if attention is not also given to the leakage flowfrom the air-cushion, it will be seen that with the conventional lay-outadopted in such an air-cushion, this flow, which escapes at the closedperiphery formed by the edge of the walla, produces a net thrust on thewall and on the vehicle of zero, i.e., the elementary thrusts have azero resultant.

If, considering FIG. '2, where similar elements have been given similarreferences, there is provided, in that part of the wall a which facesthe rear of the vehicle, a flap 3 which is flexible or is articulated atthe point 4, and if this flap is open beyond a certain vehicle speed,then the substantial flow which will escape towards the rear will thenexert a thrust tending to reduce the pressure losses and enabling theefficiency of the system to be increased.

The arrangements shown in FIGS. 1 and 2 can be combined.

Thus, there will now be described, in relation to FIGS. 3 to 12, anembodiment of a ground-effect vehicle which employs the featureshereinbefore described and which comprises other features in addition.

This apparatus comprises a central body 5 of profiled form and designed,for example, substantially on the lines of an aircraft fuselage, thus tocarry passengers as well as any other useful payload. To either side ofthe central body, between the same and the lateral faired formations 6and 7, cushions of air or pressurized fluid, in particular two series ofair-cushions, a detailed description of which will be given hereinafter,are provided. The central body 5, as well as the lateral fairings 6, 7,terminate at their bases in closed compartments 8, 9, 10, the wall ofwhich in each case, is preferably made of a flexible material forming askirt, in order to be inflatable, said compartments forming, in the restcondition, a sort of pneumatic tyre system through which the vehicle canrest upon the ground or which can also serve as buoyancy devices whenthe vehicle is resting on water.

The fairings 6, 7 can be provided at their front ends with airintakeorifices h for supplying pressurized fluid to generators d locateddownstream of said orifices.

In the example shown, four ducted fans 11 are provided at the rear ofthe vehicle for propulsion purposes, these fans or air-screws beinglocated between the wings I2, 13 of a biplane arrangement serving as avertical stabilizer and consequently being appropriately designed forthis purpose. These airscrews can be provided at other locations on thevehicle in order to give it an appropriate nominal attitude inoperation.

The propulsion can equally well be provided by other means, for exampleby dual-flow gas turbine jet engines.

The central body 5 is also terminated, at the rear, by a vertical fin l4and a rudder 15.

The terminal or top boundary of the cushion, at the side opposite thesupporting surface (ground or water) is formed in part by hollow rigidmembers 16, numbering three in the example, which connect with oneanother the central body 5 and the lateral fairings or booms 6, 7, andin part by hollow profiled bodies 17 extending between said members andparallel thereto from the central body 5 up to each of the lateralfairings or booms 6 or 7.

These hollow bodies serve to supply fluid under pressure, produced bythe generators d, and to this end are connected at one end to a duct 18extending along each of the booms 6, 7 (see FIG. At each side, over thewhole of their length, they contain a nozzle or injector 19 of slot formdirected towards the plenum chamber or the like of the cushion. Each ofthese nozzle devices serves to produce a high-velocity jet of fluid(arrow F FIG. 9), which entrains air or the surrounding fluid (arrow FFIG. 9) by a venturi effect, so that the mixture of injected fluid andentrained ambient fluid is delivered to the cushion.

The profiles of the bodies 17 are determined in such manner that eachspace between two successive bodies defines the conventionalconvergent-divergent shape of a venturi. They can be maintained inposition by cylindrical stubs 17a and 17b and possibly by brackets 35a,35b, the arrangement possibly being such that it enables the hollowbodies to expand if required.

The members or beams 16 can likewise be fitted with halfsections 16a(FIG. 7) on their walls, the interior of these sections likewise beingconnected to the duct 18 and containing a nozzle or injector arrangement19 for producing a jet.

Beneath the forward member, there is located a flap 1 which extendsbetween the central body 5 and each of the fairings or booms 6 and 7.This flap is articulated at the point 2.

Beneath the rear member 16, a flap 3 is similarly arranged, articulatedat 4. In this arrangement will be recognized the combination of flapsalready referred to in FIGS. 1 and 2.

An appropriate device can be used to place the flaps either in theposition shown in full line, or in a more or less retracted position,the position of maximum retraction being indicated by chain-dotted linesin FIG. 7 at 1a and 3a.

It will be seen that, at one side of the central body 5, thecorresponding flaps 1 and 3 delimit, in relation to the bottom structure8 of the central body, and the bottom structure 9 or 10 of the fairing 6or 7, as well as in relation to the members 16 and the profiled bodies17, a cupped or bell-shaped enclosure which defines a cushion ofpressurized fluid. This cushion is of the plenum chamber kind when theflaps occupy the position shown in full line.

Since there is a cushion of pressurized fluid at either side of thecentral body 5 and since the supply to these cushions is independent,the transverse stability is ensured. In order to secure longitudinalstability, each of these two cushions of pressurized fluid can besub-divided into two longitudinally spaced cushions by providing beneaththe central member 16 an intermediate flap 20 articulated at 21 anddesigned in the same way as the flap 1. In this manner, full automaticstabilization or trimming is achieved.

FIGS. 11 and 12 illustrate a possible embodiment of the arrangement usedto control the flaps, as well as coupling between these.

In this embodiment, the opening of the flaps is effected automaticallyunder the effect of the ram pressure of the air when the vehicle ismoving.

This effect is exerted upon the flap 1, which then pivots about its axis2 in the direction of the arrow F Through the medium of the couplinglink 24 articulated to the flap l and to the flap 20, the rotation ofthe flap 1 is transmitted to the flap 20. It is also transmitted to theflap 3, but this after a certain delay and in a reduced degree. To thisend, the flap 20 is connected to the flap 3 by a telescopic link 25, oneof the parts of said link comprising a cylinder 28 in which a piston 30can displace, the piston being connected to the other part 29 of saidlink.

As FIG. 12 shows, the piston 30 contains a bore 32 establishingcommunication between the cylinder 28 and the surrounding atmosphere byvirtue of the clearance between the rod 29 and the wall 33 of cylinder28. Under these circumstances, when flaps 1 and 20 rotate in thedirection of arrow F leaving the position shown in FIG. 11, the movementof the component 25, articulated to flap 20, is not immediatelytransmitted to the component 29 and therefore to the flap 3, the airwhich fills the cylinder 28 first of all escaping to atmosphere throughthe bore 32 and the clearance 33. The movement of the flaps 1 and 20 isonly transmitted to flap 3 when the piston 30 comes up against the wall31. Accordingly, there is both delay in the opening of the flap 3 untilsuch time as a substantial ground pressure has caused the flaps 1 and 20to pivot through a substantial angle, and in final pivoting of the flap3 through a lesser angle than thatthrough which the flaps l and 20pivot, the whole system being designed in order to maintain in theplenum chamber or the like a static pressure sufficient to maintain thevehicle in the lifted condition.

Dampers or dashpots 26a-and 26b prevent any vibration or movement by theflaps and at the same time ha.rden" the rotational deflection of theflaps to a suitable degree, in the case of the flap 1 so that it onlyoperates at a sufirciently high dynamic pressure and in the case of theflap 3 so that it resists the friction of piston 30 and cylinder 28 aswell as the air pressure in said cylinder at the start of the travel ofthe component 25.

Stops 27 fix the positions of the flaps 1, 20 and 3 while the machine ismoving at low speed and while the cushions operate as ordinary plenumchamber cushions.

The return of the flaps into this position can be effected in a varietyof ways. For example, one of the flaps 1 or 20, if their own weight' isinsufilcient to return them, can be returned by means of a mechanical orhydraulic control arrangement.

Thecontrol of the flap 3 can also be independent of that of the flaps land 20, the telescopic link 25, 29 then being discarded. A specialcontrol element, such as a jack for example, can be provided in order toenable the pilot to operate said flap.

The operation of the device is as follows:

In the rest condition, the apparatus rests on the ground or on the waterthrough the medium of the'flexible walls 8, 9 and 10. These walls aremore or less immersed when the vehicle is resting on water, as are thetips of the fiapsl, 3 and 20, which are in the positions shown in fullline.

It may be advantageous for these lower extremities of the walls8, 9 andto be at a lower level than the free edges of the flaps in order toprevent the latter from touching the ground in the rest condition withconsequent possibility of damage to them.

When it is desired to start up the vehicle, the generators d are setinto operation in order to supply the blower slots 19 in the bodies 17.The venturis, constituted by the combinations of these bodies, draw inambient air and deliver it under pressure to the chambers defining theair-cushions. The vehicle is then lifted away from contact with theground or water. By then startingup the air-screws 11, the vehicle iscaused to move in the desired way.

It will be observed that although, in this'manner, the intake of air isnot entirely except frontal as far as the supply to the generators d isconcerned, it is nevertheless effected obliquely, with only very minorchange in direction, because of the inclination of the bodies 17, thisinclination being shown in FIGS. 7 and 9.

When the speed has increased sufficiently, the opening of flaps 1 and inorder to supply the air-cushions with the ram pressure can be commenced,and the opening of flaps 3 likewise in order to enable the air to escapetowards the rear.

At high speeds, the cushions can be supplied virtually by the rampressure alone. The front flap l and the intermediate flap 20 arecompletely retracted, as shown in chain-dotted line in FIG. 7, while therear flap 3 is in an intermediate position.

Part of the fluid used to supply the cushion is then used for the liftfunction and the remainder escapes beneath the free edge of the rearflap 3, contributing to the propulsion of the vehicle.

In this configuration, the dynamic pressure is applied over the whole ofthe area offered between the forward member 16, the water or ground, thecentral body 5 and the cor responding boom 6 or 7. a

This kind of aerodynamic design makes it possible very easily to reachspeeds in excess of 200 kin/h with propulsion means which would onlymove present-day A.C.V. at substantially lower speeds.

If the hollow bodies 17 are fixed (this is the case when the brackets35a, 35b shown in FIG. 9 are present), the upward movement of the fluidtaken in can be prevented either by continuing to supply injected jetsthrough the slots 19 and at the same time reducing the pressure of thesejets, or by sealing off the spaces between the bodies 17. For example,kinds of curtains could be designed similar to roller blinds thecylinders of which would be formed in the member 16 and which wouldcompletely close off above and below the bodies 17 the intervals betweensuccessive members. It is also possible to design the bodies 17 in suchfashion that each of them can pivot about a transverse axis the line ofwhich is indicated at 22 in FIGS. 7 and 9. It will be seen in FIG. 10that each hollow body is assembled at its ends by means of a collar 22aon a fixed cylindrical stub 17a, 17b upon which it can therefore pivot(the brackets a, 35b being discarded in this case). The pivoting of thehollow bodies in the direction of the arrow F FIG. 9, makes it possible,as those skilled in the art will appreciate, to reduce the intervalbetween the successive bodies and, in the limiting condition, to closeit up altogether, the hollow bodies then resting against one another inthe manner shown in chain-dotted fashion in the right-hand part of FIG.9.

Control of the pivoting of the hollow bodies can be effected in avariety of ways. For example, they can carry arms 17d connected with oneanother by links (as shown in dotted line at 17c) and operated by thepilot, either directly or through a servornotor.

With devices of this kind, at high speeds the injected jets can ofcourse be stopped.

The structures described lend themselves furthermore to a variety ofdesigns. For example, part of the volume of the lateral booms 6, 7,above the inflatable portions 9 and 10, can

7 be used to do duty as a fuel reservoir, as shown at 23 in FIG. 8.

In addition to the advantageous indicated, the vehicle describedexhibits others too. It is well known, for example, that ground-effectvehicles of conventional design make it possible to employ a lightpayload platform because of the distribution of the lift forces overvirtually the whole of the area of said platform. However, thisadvantage is offset by the necessity to distribute the weight of thepayload equally over the whole of the area of the platform. In a machinein accordance with the invention, the payload part, in other words thecentral body 5 and for that matter the booms 6 and 7 as well, and alsotherear biplane arrangement 12, 13, is not su perimposed upon the liftsystem but is arranged side by side therewith. The part carrying thepayload is therefore the only part which requires any strengthening andthis adds very little to the all-up weightof the vehicle.

Moreover, the designer is free to select the lift systems to be greateror larger as the case may require, that is to say to appropriatelyselect the interval between the central body and the lateral booms. Thisprovides a large margin, in the choice of the pressure required in thefluid cushions for a given payload, as well as in the design conceptionof the various parts of the structure.

It will be appreciated that the embodiments described are merelyexamples and are open to modification in various ways within the scopeof the invention as defined by the appended claims.

I claim:

1. A surface efiect vehicle movable over a ground or sea surface withthe interposition of a cushion system formed between said surface and ahard ceiling structure incorporated in said vehicle, comprising:

a transverse leading flap depending from a front portion of said ceilingstructure and fonning a front boundary wall for said cushion system,said leading flap being rearwardly pivotable as said vehicle gathersspeed,

a transverse trailing flap depending from a rear portion of said ceilingstructure and forming a rear boundary wall for said cushion system, saidtrailing flap being rearwardly pivotable as said vehicle gathers speed,and

an injector-type static pump system in said ceiling structure comprisingpivotal wall means defining a venturi-like passage extending from top tobottom across said ceiling structure with a top air intake end openinginto the ambient atmosphere and a bottom discharge end opening into saidcushion system and nozzle means intermediate said ends for forming anair-entraining power jet, said venturi-like passage being rearwardlyinclined from top to bottom and being further inclinable with said wallmeans being rearwardly pivoted as said vehicle gathers speed, wherebythe general assembly of said leading flap, said trailing flap and saidstatic pump system rearwardly pivot in conjunction as the vehiclegathers speed.

2. A ground-efiect vehicle according to claim 1, wherein said wall meanscomprise a plurality of hollow profiled bodies each said body separatedfrom one another by a predetermined interval and connected to a sourceof pressurized fluid, each of said bodies being equipped with saidnozzle means, said nozzle means being in the form of tangential slots ineach said body for injecting said jets of pressurized fluid into saidpassage to cause air to flow into said cushion system, said generalassembly being retractable, as said vehicle gathers speed, substantiallyparallel to the normal direction of displacement of the vehicle, meansalso being provided whereby the ceiling of the cushion system can beclosed off from said hollow bodies defining said venturi like passages.

3. A ground-effect vehicle according to claim 1, including a centralfuselage body and lateral fairings, said cushion system comprisingair-cushions extending between said body and each said fairing.

4. A ground-effect vehicle according to claim 3, wherein the ceiling ofeach of the spaces defining the air-cushions comprises said injectortype static pump system and includes transverse members which connectsaid central body and said lateral fairings, and between which there arelocated said wall means comprising hollow bodies forming saidventuri-like passages, said front and rear transverse flaps beinglocated at each side of the central body between said body and acorresponding one of said fairings, and wherein said central body andsaid fairings comprise at their bases a flexible inflatable portionacting as a kind of pneumatic tyre through which the vehicle issupported at rest upon the supporting surface.

5. A ground-effect vehicle according to claim 1, wherein means areprovided for pivoting said leading and trailing flaps,

said means comprising hydraulic jack means, and means for rendering saidjack means inoperative so that the positions of said flaps are definedby the ram pressure of the air when the vehicle gathers speed.

6. A ground-efiect vehicle according to claim 1, wherein said leadingand trailing flaps are provided with means connecting one with theother, said connecting means including means secured to said leadingflap to cause said trailing flap to move with a predetermined degree oflag.

7. A ground-effect vehicle according to claim 6, wherein the said lastmentioned means comprises a telescopic link and means to retardtelescopic movement of said link and thereby act as a dashpot damper.

8. A vehicle as claimed in claim 1, further comprising a mechanicallinkage associated with said leading flap and said trailing flap forsynchronizing movement thereof.

9. Vehicle as claimed in claim 8, wherein said mechanical linkagecomprise delay means for causing retarded and restricted followermovement of said trailing flap compared with the movement of saidleading flap.

10. Vehicle as claimed in claim 8, further comprising dashpot meansassociated with said mechanically linked flaps for damping vibrationsthereof.

11. Vehicle as claimed in claim 1, further comprising a transverseintermediate flap depending from an intermediate portion of said ceilingstructure and forming a partition wall subdividing said cushion systeminto a forward cushion extending between said leading flap and saidintermediate flap, and a rearward cushion extending between saidintermediate flap and said trailing flap, said intermediate flap beingrearwardly pivotable as said vehicle gathers speed.

12. Vehicle as claimed in claim 11, further comprising a mechanicallinkage associated with said three flaps for synchronizing movementthereof.

13. Vehicle as claimed in claim 11, wherein said static pump systemcomprises at least one pivotal static pump in a forward part of saidceiling structure extending over said forward cushion and at least onepivotal static pump in a rearward part of ceiling structure extendingover said rearward cushion.

1. A surface effect vehicle movable over a ground or sea surface withthe interposition of a cushion system formed between said surface and ahard ceiling structure incorporated in said vehicle, comprising: atransverse leading flap depending from a front portion of said ceilingstructure and forming a front boundary wall for said cushion system,said leading flap being rearwardly pivotable as said vehicle gathersspeed, a transverse trailing flap depending from a rear portion of saidceiling structure and forming a rear boundary wall for said cushionsystem, said trailing flap being rearwardly pivotable as said vehiclegathers speed, and an injector-type static pump system in said ceilingstructure comprising pivotal wall means defining a venturi-like passageextending from top to bottom across said ceiling structure with a topair intake end opening into the ambient atmosphere and a bottomdischarge end opening into said cushion system and nozzle meansintermediate said ends for forming an airentraining power jet, saidventuri-like passage being rearwardly inclined from top to bottom andbeing further inclinable with said wall means being rearwardly pivotedas said vehicle gathers speed, whereby the general assembly of saidleading flap, said trailing flap and said static pump system rearwardlypivot in conjunction as the vehicle gathers speed.
 2. A ground-effectvehicle according to claim 1, wherein said wall means comprise aplurality of hollow profiled bodies each said body separated from oneanother by a predetermined interval and connected to a source ofpressurized fluid, each of said bodies being equipped with said nozzlemeans, said nozzle means being in the form of tangential slots in eachsaid body for injecting said jets of pressurized fluid into said passageto cause air to flow into said cushion system, said general assemblybeing retractable, as said vehicle gathers speed, substantially parallelto the normal direction of displacement of the vehicle, means also beingprovided whereby the ceiling of the cushion system can be closed offfrom said hollow bodies defining said venturi like passages.
 3. Aground-effect vehicle according to claim 1, including a central fuselagebody and lateral fairings, said cushion system comprising air-cushionsextending between said body and each said fairing.
 4. A ground-effectvehicle according to claim 3, wherein the ceiling of each of the spacesdefining the air-cushions comprises said injector type static pumpsystem and includes transverse members which connect said central bodyand said lateral fairings, and between which there are located said wallmeans comprising hollow bodies forming said venturi-like passages, saidfront and rear transverse flaps being located at each side of thecentral body between said body and a corresponding one of said fairings,and wherein said central body and said fairings comprise at their basesa flexible inflatable portion acting as a kind of ''''pneumatic tyre''''through which the vehicle is supported at rest upon the supportingsurface.
 5. A ground-effect vehicle according to claim 1, wherein meansare provided for pIvoting said leading and trailing flaps, said meanscomprising hydraulic jack means, and means for rendering said jack meansinoperative so that the positions of said flaps are defined by the rampressure of the air when the vehicle gathers speed.
 6. A ground-effectvehicle according to claim 1, wherein said leading and trailing flapsare provided with means connecting one with the other, said connectingmeans including means secured to said leading flap to cause saidtrailing flap to move with a predetermined degree of lag.
 7. Aground-effect vehicle according to claim 6, wherein the said lastmentioned means comprises a telescopic link and means to retardtelescopic movement of said link and thereby act as a dashpot damper. 8.A vehicle as claimed in claim 1, further comprising a mechanical linkageassociated with said leading flap and said trailing flap forsynchronizing movement thereof.
 9. Vehicle as claimed in claim 8,wherein said mechanical linkage comprise delay means for causingretarded and restricted follower movement of said trailing flap comparedwith the movement of said leading flap.
 10. Vehicle as claimed in claim8, further comprising dash-pot means associated with said mechanicallylinked flaps for damping vibrations thereof.
 11. Vehicle as claimed inclaim 1, further comprising a transverse intermediate flap dependingfrom an intermediate portion of said ceiling structure and forming apartition wall subdividing said cushion system into a forward cushionextending between said leading flap and said intermediate flap, and arearward cushion extending between said intermediate flap and saidtrailing flap, said intermediate flap being rearwardly pivotable as saidvehicle gathers speed.
 12. Vehicle as claimed in claim 11, furthercomprising a mechanical linkage associated with said three flaps forsynchronizing movement thereof.
 13. Vehicle as claimed in claim 11,wherein said static pump system comprises at least one pivotal staticpump in a forward part of said ceiling structure extending over saidforward cushion and at least one pivotal static pump in a rearward partof ceiling structure extending over said rearward cushion.